enumValues defined as objects create a `null` ResolverType in @graphql-codegen/visitor-plugin-common 5.6.0

[jamessharp]

Which packages are impacted by your issue?

@graphql-codegen/visitor-plugin-common

Describe the bug

Using config for enums like:

enumValues: {
  ReviewStatus: {
    {
      PREVIEW: 'preview',
      FULL: 'full',
      DISCARDED: 'discarded',
    }
  }
}

generates a resolver type for the enum of type null. E.g.

// ...
export type ResolverTypes = {
 // ...
 ReviewStatus: null;
  // ...
}

I suspect this commit is the culprit and that the logic should probably be something like

const isExternalFile = !!this.config.enumValues[typeName].sourceFile;
prev[typeName] = isExternalFile
  ? this.convertName(this.config.enumValues[typeName].typeIdentifier, {
    useTypesPrefix: false,
    useTypesSuffix: false,
  })
  : (this.config.enumValues[typeName].sourceIdentifier || this.convertName(this.config.enumValues[typeName].typeIdentifier));

Your Example Website or App

none

Steps to Reproduce the Bug or Issue

See description above

Expected behavior

The enum resolverType should be the enum, and not null.

Screenshots or Videos

No response

Platform

• OS: macOS
• NodeJS: 22
• @graphql-codegen/visitor-plugin-common version(s): 5.6.0

Codegen Config File

No response

Additional context

No response